Animals Development

Front 1

Polyspermy

Back 1

Multiple sperm fertilize the egg

Front 2

Fertilization envelope

Back 2

Resists the entry of additional sperm nuclei, slow block

Front 3

Blastomere

Back 3

Small cells formed by the cleavage partitions of one large cell

Front 4

Blastula

Back 4

Ball of cells with a fluid-filled cavitiy

Front 5

Blastocoel

Back 5

Fluid-filled cavity within the blastula

Front 6

Vegetal pole

Back 6

End of the egg where yolk is concentrated

Front 7

Animal pole

Back 7

End of the egg where yolk is significantly less concentrated

Front 8

Gastrula

Back 8

Two or three layered embryo with a primitive gut

Front 9

What is the concept of preformation?

Back 9

The idea that the egg or sperm contains a miniature infant, or “monoculus,” which becomes larger during development

Front 10

Distinguish cell differentiation from morphogenesis.

Back 10

Cell differentiation: Specialization of cells in structure and function
Morphogenesis: The process by which an animal takes shape

Front 11

What is a model organism?

Back 11

Species that are representative of larger group and easily studied. Ex. Drosophila and Caenohabditis elegans

Front 12

What constitutes the three stages of embryonic development post fertilization?

Back 12

Cleavage: Cell division creates a hollow ball of cells called a blastula
Gastrulation: Cells are rearranged into a three-layered gastrula
Organogenesis: Three layers interact and move to give rise to organs

Front 13

What is the acrosomal reaction?

Back 13

Triggered when the sperm meets the egg. Acrosome at tip of the sperm releases hydrolytic enzymes that digest material surrounding the egg.

Front 14

What is an acrosomal process?

Back 14

Sperm structure that elongates and penetrates that coat of the egg. Molecules on the tip of the process adhere to specific sperm receptor proteins that extend from the egg plasma membrane through the surrounding meshwork of extracellular matrix.

Front 15

What happens upon fusion of sperm and egg membranes?

Back 15

The fusion triggers depolarization of the membrane, a fast block to polyspermy

Front 16

What would happen if polyspermy were not prevented?

Back 16

There would be multiple fusions which would cause triploid+ embryos.

Front 17

How does the cortical reaction differ in mammals compared to other vertebrate?

Back 17

Follicles present. The cortical reaction modifies the zona pellucida, the extracellular matrix of the egg, as a slow block to polyspermy. There is no fast block, no depolarization.

Front 18

What happens after fusion of the sperm and egg membranes in mammals?

Back 18

The entire sperm is taken into the egg. The nuclei of the sperm and egg do not immediately fuse, but instead share a common spindle during the first mitotic division of the zygote.

Front 19

What is meant by the term polarity?

Back 19

Polarity: Distribution of yolk (stored nutrients)

Front 20

What is the gray crescent a marker of?

Back 20

Marks the future dorsal side of the embryo

Front 21

Contrast holoblastic and meroblastic cleavage?

Back 21

Holoblastic cleavage: Complete division of the egg (occurs in species with little or moderate amounts of yolk)
Meroblastic cleavage: Incomplete division of the egg, restricted to animal hemisphere (occurs in species with yolk-rich eggs)

Front 22

In meroblastic cleavage where does cleavage and formation of the blastocoel occur?

Back 22

Restricted to animal hemisphere.

Front 23

What are the three germ layers produced by gastrulation?

Back 23

Ectoderm: Outer layer
Endoderm: Lines digestive tract
Mesoderm: Partly fills space between the endoderm and ectoderm

Front 24

What process results in the formation of the archenteron?

Back 24

Invagination: Vegetal plate buckles inward, forms a cavity called the archenteron

Front 25

What is the open end of the archenteron called and what does it eventually become in the adult animal?

Back 25

The blastopore will become the anus

Front 26

What happens during organogenesis?

Back 26

Various regions of the germ layers develop into rudimentary organs.

Front 27

What is an amniote?

Back 27

Amniote: Organisms with embryos that develop in fluid-filled sacs in a shell or uterus

Front 28

During amniote development, four extraembryonic membranes form around the embryo, what are they called and what is their function?

Back 28

Chorion: Gas exchange
Amnion: Encloses the amniotic fluid
Yolk sac: Encloses the yolk
Allantois: Disposes of waste products and contributes to gas exchange

Front 29

What is the fate of the inner cell mass in mammals?

Back 29

Develops into the embryo and forms the extraembryonic membranes

Front 30

Which part of the blastocyst in mammals initiates implantation into the uterine wall?

Back 30

Trophoblast: Outer epithelium of the blastocyst

Front 31

What cells and tissues form the placenta?

Back 31

Trophoblast, mesodermal cells from the epiblast, and adjacent endometrial tissue

Front 32

What functions are carried out by the cytoskeleton?

Back 32

Drives cell migration, the active movement of cells. Reorganization of the cytoskeleton is associated with morphogenetic changes in embryonic tissues. Changes cell shape (ex. neural tube formation)

Front 33

What is meant by the term convergent extension?

Back 33

Convergent extension: A morphogenetic movement in which cells of a tissue become narrower and longer

Front 34

What is the cortical reaction? What does it accomplish?

Back 34

Cortical reaction: Cortical granules in the egg fuse with the plasma membrane and harden to form the fertilization envelope. The contents clip off sperm-binding receptors and cause the fertilization envelope to form. Slow block to polyspermy.